Strain distributions and electronic subband energies of self-assembled CdTe quantum wires grown on ZnTe buffer layers

Abstract

The structural properties and the shape of self-assembled CdTe/ZnTe quantum wires (QWRs) grown by using molecular beam epitaxy and atomic layer epitaxy were determined by using atomic force microscopy (AFM) measurements, and the interband transitions in the CdTe/ZnTe QWRs were investigated by using temperature-dependent photoluminescence (PL) measurements. The shape of the CdTe/ZnTe QWRs on the basis of the AFM image was modeled to be a half-ellipsoidal cylinder approximately. The temperature-dependent PL spectra showed that the PL peaks corresponding to the interband transitions from the ground electronic subband to the ground heavy-hole band (E1-HH1) shifted to lower energy with increasing temperature. Strain distributions and electronic subband energies at several temperatures were numerically calculated by using a finite-difference method (FDM) with and without taking into account shape-based strain and nonparabolicity effects. The excitonic peak corresponding to (E1-HH1) interband transitions, as determined from the PL spectra, was in reasonable agreement with that corresponding to the (E1-HH1) transitions obtained, as determined from the FDM calculations taking into account shape-based strain and nonparabolicity effects. The present results help improve understanding of the electronic structures of CdTe/ZnTe QWRs.